This thesis presents description of Genetic algorithm. The description begins with theory of complexity and following basic theory of genetic algorithm. Next part explains the principle of all three tasks – travelling salesman problem, knapsack problem and evolution of algorithm for five-in-a-row. The main focus was on developing the algorithm for five-in-a-row. The results were tested with other similar algorithms from internet. In case of travelling salesman problem and knapsack problem, the results were compared with gradient optimization methods.